Electric lamp



C. BIRDSEYE ELECTRlc LAMP .Fume 299v 37.,

Filed Oct. 17,' 1955 @www f@ Patented June 2a 1937 UNITED- STATES ELECTRIC LAMP Clarence Birdseyc, Gloucester,

Mass., assigner,

by mesne assignments, to Birdseye Electric Corporation, Dover, Del., a corporation of Dela- Application October 17, 1935, Serial No. 45,410

3 Claims.

This invention relates to incandescent lamps and consists in a novel lamp of improved lighting eiliciency and longer life than lamps heretofore known. The lamp of my invention is produced by employing a reflecting surface formed directly on the Walls of the lamp in combination with a compact coiled coil lament located in predetermined relation to the reflecting surface. The reflecting surface may be formed either upon lo the outer or inner Walls of the lamp. although it is preferred to form it upon the inner walls since in this way more effective reflection of the light rays is obtained and the reflecting surface itself is more perfectly protected. However, the 5 location of the reflecting surface is of secondary importance so longA as it is disposed so as to concentrate the light rays of the lamp in a usefully directed 'luminous eld or elds reinforced by those rays which would otherwise be wasted. 20 For direct lighting the reflecting surface may be located in a zone extending approximately from the line of maximum bulb diameter to a line in the neck of the bulb or in any other selected zone and for indirect lighting, the reflecting sur- 25 face may cover the curved end of the bulb up to the line of its maximum diameter or thereabout.

A reecting surface such as above discussed has the effect of concentrating the heat rays of the 30 filament within the lamp, raising its operating temperature and subjecting the filament and its supports to intense heat which is destructive to filaments of many types as well as'their supports. I have discovered, however, that a compact 35 coiled coil lament, preferably having a core of current-conductive material, may be advantageously employed in combination with a reflecting surface of the character discussed and may be relied upon for long life under the exacting 40 conditions to which it is subjected in use. An-

other advantage incident to the employment of a coiled coil filament in combination with a reflector equipped lamp is that on account of its compact shape and high intrinsic brilliancy, the 45 filament may be conveniently located at the approximate focus of the reflector and the light rays emanating therefrom thus effectively collected and reflected to form an intensely illuminated field.

The high operating temperature of the lamp of my invention presents a serious problem in properly supporting the filament, since al1 parts of the lament mount are subjected to the very intense heat off the concentrated heat rays. I 55 have discovered that it maybe successfully mounted upon supports of refractory metal two of which in some cases may be also utilized as the lead-in wires. Preferably and as herein shown, the supporting wires upon leaving the stem are surrounded by a shield of refractory material through which they are suitably insulated and which is permanently retained in position to protect the glass of the mount and particularly the press of the mount from overheating.

These and other features of the invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawing, in which,-

Fig. l is a view in perspective with portions broken away, of a lamp designed for indirect lighting.

Fig. 2 is a view in side elevation, partly in section, on an enlarged scale of the same lamp, and

Figs. 3 and 4 are fragmentary views on a still larger scale of alternate forms of filament such as I contemplate employing in the lamp of my invention.

Referring to the drawing, the glass bulb of the lamp is shown as being of conventional shape, including a neck portion lli which merges into an enlarged globular portion. The bulb is provided with the usual sealed-in glass stem or mount l2, containing an exhaust tube and lead-in wires i4. It may also be provided with a threaded brass base I6 of the usual construction.

The bulb herein shown is designed for indirect lighting and is provided with a peripheral refleeting surface I8 which extends completely over the curved end of the bulb and approximately to its line of maximum diameter. The reecting surface is preferably secured by depositing metallic silver upon the inside of the bulb in accordance with the method disclosed in the co-pending application of Pincus Deren, Serial No. 42,227, filed September 26, 1935, although the present invention is not limited to a reflector of any specic characteristics. The intermediate parts of the bulb are frosted or etched in an area 20 which extends from the boundary of the reflecting surface to a line within the neck of the bulb. The light passing through the bulb is thus diffused by the frosted surface and shadow effects are eliminated.

As will be apparent, the action of the reecting surface i8 is to intercept all the light rays of the lamp which would otherwise pass downwardly and direct them upwardly in a definite and concentrated luminous field. The most effective reecting condition is secured when the filament reflecting surface, and in the lamp herein illustrated this is effected by' employing a filament of filed April 10, 1935, and which comprises a wire helix arranged in substantially continuous contact with a core of current-conductive material and wound withvits core into a helix, in other words, a double or triple coiled coil having a permanent core within its primary turns. The construction of such a double coiled filament is illustrated in Fig. 4 in which a. core 22 of tungsten Wire or the like has coiled thereon a wire 24, and then the wound core itself is formed into a coreless helix. The coiled coil lament 26 of the character indicated is supported in position by three supporting rods or wires of refractory or high melting-point metal such as tungsten. Of these, two supports comprise the lead-in wires I4 which are flattened and bent over at theirends to clamp the ends of the filament. The third support 28 is formed of similar material and embedded or anchored in the glass mount I2.

'Ihe glass mount I2 has a flattened press at its inner end through which the lead-in wires I4 pass and in which the end of the supporting wire 28 is embedded. The mount I2 is shorter than the neck III o'f the bulb, being terminated at the greatest practicable distance from the lament and remote from the intensely hot focus of the heat rays in the lamp. The mount is further protected by a shield in the shape of a disk 30 of metal or mica which is supported beyond the end of the stem by Ia wire 32 embedded in the press of the stem I2 and projecting downwardly from its end. The end of the wire 32 is bent at right angles and secured to the outer face of the disk 30 as shown in Fig. 1. This represents but one convenient construction for positioning the shield in the desired location in the bulb. Preferably, and as herein shown, the lead-in wires I 4.'

and the supporting wire 28 are insulated as they pass from the press by individual insulating tubes 34v of refractory material. The tubes 34 may be fused or otherwise secured to the end of the mount, I2, and at their lower ends extend somewhat beyond the disk 30. y

I have illustrated my invention as embodied in a lamp intended for indirect lighting and it will be clear that in a lamp intended for direct lighting constructed in accordance with this invention the reflecting zone will occupy the upper portions of the walls of the lamp, the filament will be located within the confines thereof, and the luminous eld will be defined by the clear or etched lower portion of the bulb and may compose a 60 cone of light. In this case the shield 3B may be utilized as a reflector for those rays which would otherwise be lost in the neck of the bulb.

In Fig. 3 is shown a fragment of triple coil coiled lament which in some lamps I prefer 9,034,990 l is located substantially at the focus or the eux-vea dex-stood that the filament used in the lamp of my invention is in all cases compact and rugged in construction and of high intrinsic brilliancy. It is located in the bulb in the most favorable location possible for lighting efficiency. It is supported moreover by means capable of withstanding extremely high working temperatures and the more delicate parts of the lamp, such as the mount I2, are not only located as remotely Aas practicable from the focus of the heat rays, but are also shielded effectually from the direct action thereof.

. The combination of my invention presents the additional advantage of long lamp life with full color pattern or composition of light. I have found that it is entirely practicable to operate a coiled coil filament at full temperature ln a reectorlamp of the character herein shown for well upward of 1000 hours, whereas other iliaments must be operated at a somewhat reduced temperature inthese lamps in order to give ports of the character above discussed, I am able to produce an improved lamp having greater lighting efilciency and longer life than any lamps heretofore available to themarket. I have found these lamps particularly satisfactory and ef-a cient in 150, 200 and 300 watt and larger sizes, although the invention hasl a wider range of application. Y

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is,

1. An incandescent electric lamp comprising, in combination, an oversize bulb provided on a portion of its inner surface with a metallic reflecting surface, a coiled coil filament of compact shape located substantially-at the focus of said reecting surface and adapted to burn at a high temperature and with a high intrinsic brilliancy, a glass mount in the neck of the bulb, refractory metal ,supports for the filament projecting :from said mount, and a heat-reilecting and light-refleeting shield supported in position to protect thepress of the mount from the heat developed in the lamp.

2. An incandescent electric lamp comprising, in combination, an oversize bulb provided on a portion of its inner walls with a metallic reecting surface, a.coiled coil filament located sub-` stantially at the focus of said reflecting surface and adapted to operate at high temperature, with. high intrinsic brilliancy and with the development of excessive heat, the said metallic surface being located by the oversize bulb at a sumcient distance from the filament to escape deterioration by heat, refractory metal supports located within the area subject to direct heat radiation from the lament and concentrated heat reflection from said metallic reflecting surface, a glass mount for said supports, anda neck reflector so located as to protect said mount from the heat developed in the lamp and increase the intensity of light emitted thereby.

3. An incandescent electric lamp comprising,

in combination, an oversize bulb provided on its 15 inner walls with a metallic reflecting surface, and having a frosted light-emitting area, a glass mount in the neck of the bulb, a compact coiled coil ilament located partially in the focus of said reflecting surface and adapted to operate at high temperature with the development of excessive heat and with high intrinsic brilliancy, the oversize bulb serving to locate the metallic surface at a distance sufllciently remote from the lament to safeguard it from heat damage, refractory metal supports for the illament, and a neck reector adapted to reflect away from the mount the greater part of the intense radiation from the filament, the frosted area of the bulb serving to diffuse the intense light radiation from the compact and brilliant lament.

CLARENCE BIRDSEYE. 

